1. Field of the Invention
The invention concerns cosmetic compositions of improved aesthetic properties having low pH and containing organic sunscreen agents.
2. The Related Art
Sunscreen agents are commonly used in compositions intended for cosmetic application to the face and other exposed skin areas. These preparations are formulated as creams, lotions or oils containing as the agent an organic ultraviolet radiation absorbing chemical compound. The agent blocks passage of erythematogenic radiation thereby preventing its penetration into the skin.
High quality skinfeel properties are not always easy to achieve where the compositions contain sunscreen agents. The challenge is especially magnified with low pH systems. Organic sunscreens often have a sticky or tacky feel. These attributes must be counteracted when formulated into an aqueous emulsion composition. Formulating an aesthetically pleasant system incorporating these actives remains a challenge to chemists.
Sunscreen compositions have been well documented in the patent literature. For instance, U.S. Pat. No. 5,505,935 (Guerrero et at.) discloses sunscreen compositions wherein ethylene/vinyl acetate copolymer and poly(methyl methacrylate) particles were found useful as boosters for the sun protection factor (SPF).
Accordingly, it is an advantage of the present invention to provide an organic sunscreen agent formulated cosmetic composition with improved skinfeet, especially one with low tackiness.
Another advantage of the present invention is to provide a sunscreen agent formulated cosmetic composition that is an aqueous emulsion of low pH having good skinfeel properties.
These and other advantages of the present invention will become more apparent from consideration of the summary and detailed discussion which follows.
A cosmetic composition is provided which includes:
(i) from about 0.1 to about 15% by weight of an organic sunscreen agent having a chromophoric group active within the ultraviolet radiation range from 290 to 400 nm;
(ii) from about 0.01 to about 10% by weight of a water-insoluble powdered polymer formed as porous particles having an Oil Absorbance (castor oil) value ranging from about 90 to about 500 ml/100 gm; and
(iii) from about 1 to about 99% of water, the composition having a pH of less than 7.
Now it has been found that water-insoluble polymeric powders in porous particle form can modify the tacky skinfeel normally associated with organic sunscreen agents. Excellent skinfeel without any perceptible tackiness is achieved, even in systems having extremely low pH.
A first element of compositions according to the present invention is that of a water-insoluble material in the form of polymeric porous spherical particles. By the term xe2x80x9cporousxe2x80x9d is meant an open or closed cell structure. Preferably the particles are not hollow beads. Average particle size may range from about 0.1 to about 100, preferably from about 1 to about 50, more preferably greater than 5 and especially from 5 to about 15, optimally from about 6 to about 10 micron. Organic polymers or copolymers are the preferred materials and can be formed from monomers including the acid, salt or ester forms of acrylic acid, methacrylic acid, methylacrylate, ethylacrylate, ethylene, propylene, vinylidene chloride, acrylonitrile, maleic acid, vinyl pyrrolidone, styrene, butadiene and mixtures thereof. The polymers are especially useful in cross-linked form. Cells of the porous articles may be filled by a gas which can be air, nitrogen or a hydrocarbon. Oil Absorbance (castor oil) is a measure of porosity and may range from about 90 to about 500, preferably from about 100 to about 200, optimally from about 120 to about 180 ml/100 grams. Density of the particles may range from about 0.08 to 0.55, preferably from about 0.15 to 0.48 g/cm3.
Illustrative porous polymers include polymethylmethacrylate and cross-linked polystyrene. Most preferred is polymethyl methacrylate available as Ganzpearl(copyright) 820 available from Presperse, Inc., Piscataway, N.J., known also by its INCI name of Methyl Methacrylate Crosspolymer.
Amounts of the water-insoluble polymeric porous particles may range from about 0.01 to about 10%, preferably from about 0.1 to about 5%, optimally from about 0.3 to about 2% by weight of the composition.
A second element of compositions according to the present invention is that of an organic sunscreen agent having at least one chromophoric group absorbing within the ultraviolet ranging from 290 to 400 nm. Chromophoric organic sunscreen agents may be divided into the following categories (with specific examples) including: p-Aminobenzoic acid, its salts and its derivatives (ethyl, isobutyl, glyceryl esters; p-dimethylaminobenzoic acid); Anthranilates (o-aminobenzoates; methyl, menthyl, phenyl, benzyl, phenylethyl, linalyt, terpinyl, and cyclohexenyl esters); Salicylates (octyl, amyl, phenyl, benzyl, menthyl, glyceryl, and dipropyleneglycol esters);
Cinnamic acid derivatives (menthyl and benzyl esters, alpha-phenyl cinnamonitrile; butyl cinnamoyl pyruvate); Dihydroxycinnamic acid derivatives (umbelliferone, methylumbelliferone, methylaceto-umbelliferone); Trihydroxycinnamic acid derivatives (esculetin, methylesculetin, daphnetin, and the glucosides, esculin and daphnin); Hydrocarbons (diphenylbutadiene, stilbene); Dibenzalacetone and benzalacetophenone; Naphtholsulfonates (sodium salts of 2-naphthol-3,6-disulfonic and of 2-naphthol-6,8-disulfonic acids); Dihydroxy-naphthoic acid and its salts; o- and p-Hydroxybiphenyldisulfonates; Coumarin derivatives (7-hydroxy, 7-methyl, 3-phenyl); Diazoles (2-acetyl-3-bromoindazole, phenyl benzoxazole, methyl naphthoxazole, various aryl benzothiazoles); Quinine salts (bisulfate, sulfate, chloride, oleate, and tannate); Quinoline derivatives (8-hydroxyquinoline salts, 2-phenylquinoline); Hydroxy- or methoxy-substituted benzophenones; Uric and vilouric acids; Tannic acid and its derivatives (e.g., hexaethylether); (Butyl carbityl) (6-propyl piperonyl) ether; Hydroquinone; Benzophenones (Oxybenzone, Sulisobenzone, Dioxybenzone, Benzoresorcinol, 2,2xe2x80x2, 4,4xe2x80x2-Tetrahydroxybenzophenone, 2,2xe2x80x2-Dihydroxy-4,4xe2x80x2-dimethoxybenzophenone, Octabenzone; 4-lsopropyldibenzoylmethane; Butylmethoxydibenzoylmethane; Etocrylene; and 4-isopropyl-dibenzoylmethane).
Particularly useful are: 2-ethylhexyl p-methoxycinnamate, 4,4xe2x80x2-t-butyl methoxydibenzoylmethane, 2-hydroxy-4-methoxybenzophenone, octyidimethyl p-aminobenzoic acid, digalloyLtrioleate, 2,2-dihydroxy-4-methoxybenzophenone, ethyl 4-[bis(hydroxypropyt)]aminobenzoate, 2-ethylhexyl-2-cyano-3,3-diphenylacrylate, 2-ethythexylsalicytate, glyceryl p-aminobenzoate, 3,3,5-trimethytcyclohexylsaticylate, methylanthranitate, p-dimethylaminobenzoic acid or aminobenzoate, 2-ethylhexyl p-dimethylaminobenzoic, 2-phenytbenzimidazole-5-sulfonic acid, 2-(p-dimethylaminophenyl)-5-sulfoniobenzoxazoic acid and mixtures thereof.
Suitable commercially available organic sunscreen agents are those identified under the following table.
Amounts of the organic sunscreen agent will range from about 0.1 to about 15%, preferably from about 0.5% to about 10%, optimally from about 1% to about 8% by weight of the composition.
Compositions of the present invention wilt contain water in amounts 5 from about 1 to about 99%, preferably from about 5 to about 90%, more preferably from about 35 to about 70%, optimally between about 40 and about 60% by weight. Ordinarily the compositions will be water and oil emulsions of the W/O or O/W variety.
Compositions of the present invention wilt have a pH less than 7, preferably ranging from about 1 to 6.8, more preferably ranging from about 1 to about 6.5, still more preferably from about 2.5 to about 4.5, optimally from about 3 to about 3.8.
Where the compositions are emulsions, they may comprise emollient materials in the form of mineral oils, silicone oils and synthetic or natural esters. Amounts of the emollients may range from about 0.1 to about 30%, preferably between about 0.5 and 20% by weight.
Silicone oils may be divided into the volatile and non-volatile variety. The term xe2x80x9cvolatilexe2x80x9d as used herein refers to those materials which have a measurable vapor pressure at ambient temperature. Volatile silicone oils are preferably chosen from cyclic or linear polydimethylsiloxanes containing from about 3 to about 9, preferably from about 4 to about 5, silicon atoms.
Linear volatile silicone materials generally have viscosities less than about 5 centistokes at 25xc2x0 C. while cyclic materials typically have viscosities of less than about 10 centistokes.
Nonvolatile silicone oils useful as an emollient material include polyalkyl siloxanes, polyalkylaryl siloxanes and polyether siloxane copolymers. The essentially non-volatile polyalkyl siloxanes useful herein include, for example, polydimethyl siloxanes with viscosities of from about 5 to about 100,000 centistokes at 25xc2x0 C.
Among suitable ester emollients are:
(1) Alkenyl or alkyl esters of fatty acids having 10 to 20 carbon atoms. Examples thereof include isopropyl palmitate, isopropyl isostearate, isononyl isonanonoate, oleyl myristate, oleyl stearate, and oleyl oleate.
(2) Ether-esters such as fatty acid esters of ethoxylated fatty alcohols.
(3) Polyhydric alcohol esters. Ethylene glycol mono and di-fatty acid esters, diethylene glycol mono- and di-fatty acid esters, polyethylene glycol (200-6000) mono- and di-fatty acid esters, propylene glycol mono- and di-fatty acid esters, polypropylene glycol 2000 monooleate, polypropylene glycol 2000 monostearate, ethoxylated propylene glycol monostearate, glyceryl mono- and di-fatty acid esters, polyglycerol poly-fatty esters, ethoxylated glyceryl mono-stearate, 1,3-butylene glycol monostearate, 1,3-butylene glycol distearate, polyoxyethylene polyol fatty acid ester, sorbitan fatty acid esters, and polyoxyethylene sorbitan fatty acid esters are satisfactory polyhydric alcohol esters.
(4) Wax esters such as beeswax, spermaceti, myristyl myristate, stearyl stearate.
(5) Sterols esters, of which soya sterol and cholesterol fatty acid esters are examples thereof.
The most preferred esters are dicaprytyl ether and isopropyl isostearate.
Fatty acids having from 10 to 30 carbon atoms may also be included in the compositions of this invention. Illustrative of this category are pelargonic, tauric, myristic, palmitic, stearic, isostearic, hydroxystearic, oleic, linoleic, ricinoleic, arachidic, behenic and erucic acids.
Humectants of the polyhydric alcohol-type may also be included in the compositions of this invention. The humectant aids in increasing the effectiveness of the emollient, reduces scaling, stimulates removal of built-up scale and improves skin feel. Typical polyhydric alcohols include glycerol (also known as glycerin), polyalkylene glycols and more preferably alkylene polyols and their derivatives, including propytene glycol, dipropylene glycol, polypropylene glycol, polyethylene glycol and derivatives thereof, sorbitol, hydroxypropyl sorbitol, hexylene glycol, 1,3-butylene glycol, 1,2,6-hexanetriol, ethoxylated glycerol, propoxylated glycerol and mixtures thereof. For best results the humectant is preferably glycerin. The amount of humectant may range anywhere from 0.5 to 30%, preferably between 1 and 15% by weight of the composition.
Cosmetic compositions of the present invention may be in any form. These forms may include lotions, creams, roll-on formulations, mousses, aerosol sprays and cloth- or pad-apptied formulations.
Emulsifiers may also be present in cosmetic compositions of the present invention. Total concentration of the emulsifier may range from about 0.1 to about 40%, preferably from about 1 to about 20%, optimally from about 1 to about 5% by weight of the total composition. The emulsifier may be selected from the group consisting of anionic, nonionic, cationic and amphoteric actives. Particularly preferred nonionic surfactants are those with a C10-C20 fatty alcohol or acid hydrophobe condensed with from about 2 to about 100 moles of ethylene oxide or propylene oxide per mote of hydrophobe; C2-C10 alkyl phenols condensed with from 2 to 20 motes of alkylene oxide; mono- and di- fatty acid esters of ethylene glycol; fatty acid monoglyceride; sorbitan, mono- and di- C8-C20 fatty acids; and polyoxyethylene sorbitan as well as combinations thereof. Alkyl polyglycosides and saccharide fatty amides (e.g. methyl gluconamides) are also suitable nonionic emulsifiers.
Preferred anionic emulsifiers include soap, alkyl ether sulfate and sulfonates, alkyl sulfates and sulfonates, alkylbenzene sulfonates, alkyl and dialkyt sulfosuccinates, C8-C20 acyl isethionates, C8-C20 alkyl ether phosphates, alkylethercarboxylates and combinations thereof.
Preservatives can desirably be incorporated into the cosmetic compositions of this invention to protect against the growth of potentially harmful microorganisms. Suitable traditional preservatives for compositions of this invention are alkyl esters of para-hydroxybenzoic acid. Other preservatives which have more recently come into use include hydantoin derivatives, propionate salts, and a variety of quaternary ammonium compounds. Cosmetic chemists are familiar with appropriate preservatives and routinely choose them to satisfy the preservative challenge test and to provide product stability. Particularly preferred preservatives are iodopropynyl butyl carbamate, phenoxyethanol, methyl paraben, propyl paraben, imidazolidinyl urea, sodium dehydroacetate and benzyl alcohol. The preservatives should be selected having regard for the use of the composition and possible incompatibilities between the preservatives and other ingredients in the emulsion. Preservatives are preferably employed in amounts ranging from about 0.01% to about 2% by weight of the composition.
Thickening agents may be included in compositions of the present invention. Particularly useful are the polysaccharides. Examples include starches, natural/synthetic gums and cellulosics. Representative of the starches are chemically modified starches such as aluminum starch octenylsuccinate. Suitable gums include xanthan, sclerotium, pectin, karaya, arabic, agar, guar, carrageenan, alginate and combinations thereof. Suitable cellulosics include hydroxypropyl cellulose, hydroxypropyl methylcellulose, ethylcellulose and sodium carboxy methylcellulose. Synthetic polymers are still a further class of effective thickening agent. This category includes crosslinked polyacrylates such as the Carbomers, polyacrylamides such as Sepigel(copyright) 305 and taurate copolymers such as Aristoflex(copyright) AVC, the latter identified by its INCI nomenclature of Acryloyl Dimethyltaurate/Vinyl Pyrrolidone Copolymer.
Amounts of the thickener may range from about 0.001 to about 5%, preferably from about 0.1 to about 2%, optimally from about 0.2 to about 0.5% by weight.
For additional thickening, it is preferred to have magnesium aluminum silicate, commercially available as Veegum(copyright), sold by the R.T. Vanderbilt Company. Amounts of this inorganic thickening agent may range from about 0.01 to about 10%, preferably from about 0.5 to about 1.2% by weight.
Optionally the compositions may include an alpha- or beta-hydroxycarboxylic acid. Most preferred are the free acid, salts or esters of glycolic acid, lactic acid, 2-hydroxyoctanoic acid, gluconolactone and mixtures thereof. Amounts of these materials may range from about 0.01 to about 20%, preferably from about 0.2 to about 10%, optimally from about 1 to about 5% by weight.
Minor adjunct ingredients may also be present in the cosmetic compositions. Among them may be the vitamins such as Vitamin A Palmitate, Vitamin C and derivatives (e.g. ascorbyl palmitate or magnesium ascorbyl phosphate), Vitamin E Acetate and DL-panthenol. Also useful are: retinol, ceramides and herbal extracts including green tea and chamomile.
Colorants, fragrances and abrasives may also be included in compositions of the present invention. Each of these substances may range from about 0.05 to about 5%, preferably between 0.1 and 3% by weight.
Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material ought to be understood as modified by the word xe2x80x9caboutxe2x80x9d.
The term xe2x80x9ccomprisingxe2x80x9d is meant not to be limiting to any subsequently stated elements but rather to encompass non-specified elements of major or minor functional importance. In other words the listed steps, elements or options need not be exhaustive. Whenever the words xe2x80x9cincludingxe2x80x9d or xe2x80x9chavingxe2x80x9d are used, these terms are meant to be equivalent to xe2x80x9ccomprisingxe2x80x9d as defined above.
The following Examples will more fully illustrate the embodiments of this invention. All parts, percentages and proportions referred to herein and in the appended claims are by weight unless otherwise indicated.